In this proposed work, using state-of-the art computer assisted instruction (CAI), we will address internationally recognized difficulties in providing consistent, high quality learning environments that ensure clinical competence for novice physicians-in-training. Frequently, computer-based simulations and instructional modules are developed and implemented into medical training without adequate attention to effective instructional design or meaningful assessment of educational outcomes. If effective, these tools have the potential to fill major educational gaps caused by rapidly changing or resource poor health care delivery environments in which most physician training occurs. This would be especially the case for trainees at some distance from an Academic Medical Center (AMC). If not effective, then fundamental work needs to be done to improve the educational value of these learning tools before further investment in and diffusion of such technology, especially when the stakes are as high as in the training of physicians. Along with my collaborators in educational psychology, surgical education and computer science, and drawing on our experience in multi-institutional collaborative medical education research, we will capitalize on a unique opportunity to rigorously study the effectiveness of the Web Initiative in Surgical Education (WISE-MD), a 25 module, case based, rich media, core curriculum in surgical education that is endorsed by the American College of Surgeons and the Association of Surgical Education. The goal of the WISE-MD curriculum is to fast-forward the development of clinical reasoning in novice medical students. We propose a rigorous, 2 year, 3-armed randomized controlled trial to assess the effectiveness of example WISE-MD modules on both cognitive and affective aspects of learning clinical reasoning, a critical and complex construct. With this design we compare 2 instructional design approaches to CAI: 1) limited interactivity CAI and 2) enhanced interactivity CAI features, which are costly to produce and implement (e.g. interactive physical exams) with each other and to the standard clinical clerkship experience. This is important to do because, despite enthusiasm for the 7 existing WISE-MD modules (they are required curriculum in 22 medical schools), which attests to the face validity of the modules, we do not yet have the evidence to determine what are necessary instructional design features of CAI and what the relative educational value of CAI in the clinical education of medical students, compared to the traditional curriculum they currently receive. In addition, in this design we will be able to assess a number of CAI attribute-student aptitude interactions such as the impact on student achievement of the nature of the clinical case ("case effect") and a number of important variables known to modify the relationship between instructional method and achievement including individual learner variables, and curriculum structure and content. Finally, collaboration on this substantial project allows us to address challenges to standardizing curriculum and medical education research posed by differing institutional cultures, information technology infrastructures, technical capabilities and resources including, and especially, faculty time.